High-resolution Micro-computed Tomography Research Articles

Morphological adaptations of the mouthparts to the ectoparasitic lifestyle of the biting midge Forcipomyia paludis (Diptera: Ceratopogonidae), specialized in Odonata

Damselflies and dragonflies are well-known hosts of the West Palaearctic biting midge Forcipomyia paludis. Females of this ectoparasitic dipteran mainly cling to the host’s wings, sucking hemolymph from the wing veins. The midges are firmly attached to the wing surface with specialized tarsi, thus not being flung away during the host’s flight maneuvers. As for another ceratopogonid—F. odonatophila from New Guinea—had been suggested, we assumed that in F. paludis, the attachment would be reinforced by the mouthparts during the suction action. In the present study, we used behavioral field observations, scanning electron microscopy (SEM) and high-resolution micro-computed tomography (µCT), to study the mouthparts of F. paludis. We focused on the mouthpart configuration post sucking and thus on the contact with the host's wing as well as on the piercing process into the wing veins. We foster our understanding of F. paludis being a parasite of Odonata by showing proof of the piercing and therefore the sucking of hemolymph from the wings. Additionally, the mouthparts clearly show contamination with odonate wing wax after the sucking procedure. Furthermore, we discuss probable additional functions of the piercing process for the firm attachment to the flying host of F. paludis.

Abstract 132: Reduction Of Bone Quality In A Murine Model Of Essential Hypertension Relative To Age

Autoimmune and inflammatory diseases such as obesity and cancer are highly linked to altered bone growth and osteoporosis. Hypertension (HTN) is an inflammatory condition associated with reduced bone mineral density and increased risk for fragility fractures in adults. As cases of pediatric HTN rise in the United States, HTN may increase bone loss in children and future risk for osteoporosis. We hypothesized that HTN-induced osteoporosis in young mice reduces bone quality like that of aging. To assess this, 3.5- or 16-month-old male C57BL/6J mice received Angiotensin (Ang) II (490 ng/kg/day) or vehicle infusion by subcutaneous osmotic mini-pumps. After 6-weeks of infusion, the lumbar vertebral bodies (VB) were harvested, and analyzed by high-resolution micro-computed tomography and finite element analysis. In young mice, Ang-II induced HTN caused reductions in bone volume fraction (33.4 ± 0.8 vs 25.4 ± 1.1 %, p<0.0001) and trabecular thickness (66.4 ± 1.1 vs 54.3 ± 1.5 μm, p<0.0001). HTN reduced the estimated failure force (24.3 ± 0.7 vs 16.1 ± 1.1 N, p<0.0001) in young mice. In contrast to young mice, in aged mice Ang-II infusion did not induce bone loss; however, at baseline, the old mice exhibited reduced bone quality like that of hypertensive young mice: bone volume fraction (22.5 ± 0.7 vs 25.4 ± 1.1 %, p=0.2928), trabecular thickness (58.0 ± 1.5 vs 54.3 ± 1.1 μm, p=0.3866), and estimated failure force (17.6 ± 0.8 vs 16.1 ± 1.1 N, p=0.6517). To ascertain the impact of inflammation in the bone marrow microenvironment, the bone marrow was analyzed by flow cytometry. The number of CD4 + T cells producing IL-17A was increased in hypertensive vs normotensive young mice (230.0 ± 8.9 vs 167.3 ± 16.6 cells per 1 million events, p=0.0035), as were dendritic cells (408.3 ± 29.1 vs. 229.1 ± 20.5 cells per 1 million events, p<0.0001). CD4 + T cells producing IFN-γ also rose (2845 ± 129 vs 2437 ± 174 cells per 1 million events, p=0.07) in young hypertensive mice. Both normotensive and hypertensive old mice experienced overactive inflammatory responses compared to the young group. Thus, HTN mimics aspects of aging on bone health, causing inflammation in the bone marrow and osteoporosis. Efforts to detect and treat HTN in children may deter untoward events related to bone loss in adulthood.

Using X-ray Micro-Computed Tomography to Three-Dimensionally Visualize the Foregut of the Glassy-Winged Sharpshooter (Homalodisca vitripennis).

Simple SummaryThe foregut of the glassy-winged sharpshooter is difficult to dissect and observe in three dimensions with SEM or TEM. We describe an X-ray micro-computed tomography (microCT)-based method for studying the GWSS foregut including the precibarium and the cibarium, with high resolution. MicroCT imaging showed great promise for the study of the tissues and structures of small insects.Dissecting the heads of small insects belonging to the order Hemiptera for detailed anatomical investigation with light or scanning electron microscopy is difficult, time-consuming, and destructive, often resulting in sample preparation artifacts. Nevertheless, the structural details of these insects often hold critical information regarding their interactions with bacterial pathogens. For example, the glassy-winged sharpshooter (GWSS) is an efficient vector of the bacterium Xylella fastidiosa, the causal agent of Pierce’s disease in grape vines, but the foregut of this species is exceptionally difficult to dissect. Here, we describe a simple, non-destructive method to investigate the structure of the anterior gut of GWSS using high-resolution micro-computed X-ray tomography (microCT). The use of microCT eliminates the need for destructive dissection and reveals the morphology of small insects in three dimensions, allowing the user to virtually dissect the sample. The use of microCT imaging is a promising and powerful tool in the entomological sciences for studying the structures of vector insects, especially for difficult-to-dissect regions such as the foregut.

Integrating particle tracking with computational fluid dynamics to assess haemodynamic perturbation by coronary artery stents.

AimsCoronary artery stents have profound effects on arterial function by altering fluid flow mass transport and wall shear stress. We developed a new integrated methodology to analyse the effects of stents on mass transport and shear stress to inform the design of haemodynamically-favourable stents.Methods and resultsStents were deployed in model vessels followed by tracking of fluorescent particles under flow. Parallel analyses involved high-resolution micro-computed tomography scanning followed by computational fluid dynamics simulations to assess wall shear stress distribution. Several stent designs were analysed to assess whether the workflow was robust for diverse strut geometries. Stents had striking effects on fluid flow streamlines, flow separation or funnelling, and the accumulation of particles at areas of complex geometry that were tightly coupled to stent shape. CFD analysis revealed that stents had a major influence on wall shear stress magnitude, direction and distribution and this was highly sensitive to geometry.ConclusionsIntegration of particle tracking with CFD allows assessment of fluid flow and shear stress in stented arteries in unprecedented detail. Deleterious flow perturbations, such as accumulation of particles at struts and non-physiological shear stress, were highly sensitive to individual stent geometry. Novel designs for stents should be tested for mass transport and shear stress which are important effectors of vascular health and repair.

Cerebral arterial and ventricular morphology of the dogfish (Squalus acanthias), American bullfrog (Rana catesbeiana), and green iguana (Iguana iguana): Arterial high-resolution micro-CT, dissection, and radiography study.

This study's objective was to investigate obtaining high-resolution micro-computed tomography (CT) imaging of the injected arterial circulation of the brains of the dogfish (Squalus acanthias), American bullfrog (Rana catesbeiana), and green iguana (Iguana iguana). No micro-CT images of the arterial morphology of the brains of these vertebrates were previously published. Micro-CT imaging was performed on brains that had the cerebral arterial and ventricular systems injected with a radiopaque barium-gelatin compound in the early 1970s. These specimens were dissected and placed in a preservative fluid for 35 years, until imaged with micro-CT. The obtained micro-CT images were processed with a software program that provided 3D rotational motion rendering, and sequential display of 2D renderings of the micro-CT data. The anatomic information provided by the high-resolution micro-CT is not reproducible by any other radiopaque contrast currently available, without tissue removal corrosion, and enhanced the dissection information. The digital videos of the micro-CT 3D rotational motion rendering and sequential display of 2D renderings of the dogfish, bullfrog, and green iguana, demonstrate the extent of the arterial network within the brain, the arterial segments obscured by overlying structures such as nerves, and identified in the bullfrog the venous cerebral circulation resulting from the centrifugal leptomeningeal arterial capillaries. The rotational 3D images separated superimposed arterial structures, and the sequential display of the 2D renderings clarifies the relationship of cut or overlapped arterial branches. Comparing the brain and arterial morphology of the dogfish, bullfrog, and green iguana demonstrates some of the evolutionary modifications in these vertebrates.

Osteology of the caecilian Gegeneophis carnosus (Beddome, 1870) (Amphibia: Gymnophiona: Grandisoniidae) from the Western Ghats of peninsular India

Abstract The osteology of the poorly known grandisoniid caecilian Gegeneophis carnosus is described for the first time by applying high-resolution X-ray micro-computed tomography to some recently collected material. The ossified skeleton comprises a stegokrotaphic skull, lower jaw, and vertebral column. The braincase, composed of the sphenethmoid and os basale, is covered by eight other cranial elements viz. nasopremaxilla, frontal, parietal, squamosal, pterygoquadrate, maxillopalatine, vomer, and stapes. The eye is covered by the maxillopalatine, and an (open) orbit is absent. The sphenethmoid is not exposed and lacks a solum nasi or a ventral flange. The olfactory chamber lacks an olfactory eminence. Slight asymmetries were observed in the structure and/or size of the left and right frontals and parietals and in the number and size of some foramina. Except for pterygoquadrate and stapes, all bones are pierced by foramina for nerves and/or blood vessels. The lower jaw shows a typical caecilian pattern with dentigerous pseudodentary and edentulous pseudoangular. Numbers of vertebrae range from 123–130 (mean 126). The vertebrae are somewhat heterogenous, varying in size and proportions along the column. Comparisons are made with other caecilians, especially other grandisoniids. Aspects of the cranial osteology of Gegeneophis, such as the closed orbit, subterminal mouth, and stegokrotaphy are possible adaptations to dedicated fossoriality, but functional, behavioural, and field ecological data are not yet available to test this.

Low radiodensity μCT scans to reveal detailed morphology of the termite leg and its subgenual organ

Termites sense tiny substrate-borne vibrations through subgenual organs (SGOs) located within their legs' tibiae. Little is known about the SGOs' structure and physical properties. We applied high-resolution (voxel size 0.45 μm) micro-computed tomography (μCT) to Australian termites, Coptotermes lacteus and Nasutitermes exitiosus (Hill) to test two staining techniques. We compared the effectiveness of a single stain of Lugol's iodine solution (LS) to LS followed by Phosphotungstic acid (PTA) solutions (1% and 2%). We then present results of a soldier of Nasutitermes exitiosus combining μCT with LS + 2%PTS stains and scanning electron microscopy to exemplify the visualisation of their SGOs. The termite's SGO due to its approximately oval shape was shown to have a maximum diameter of 60 μm and a minimum of 48 μm, covering 60 ± 4% of the leg's cross-section and 90.4 ± 5% of the residual haemolymph channel. Additionally, the leg and residual haemolymph channel cross-sectional area decreased around the SGO by 33% and 73%, respectively. We hypothesise that this change in cross-sectional area amplifies the vibrations for the SGO. Since SGOs are directly connected to the cuticle, their mechanical properties and the geometric details identified here may enable new approaches to determine how termites sense micro-vibrations.

Acetabular Reaming Is a Reliable Model to Produce and Characterize Periarticular Heterotopic Ossification of the Hip.

Heterotopic ossification (HO) is a pathologic process characterized by the formation of bone tissue in extraskeletal locations. The hip is a common location of HO, especially as a complication of arthroplasty. Here, we devise a first-of-its-kind mouse model of post-surgical hip HO and validate expected cell sources of HO using several HO progenitor cell reporter lines. To induce HO, an anterolateral surgical approach to the hip was used, followed by disclocation and acetabular reaming. Animals were analyzed with high-resolution roentgenograms and micro-computed tomography, conventional histology, immunohistochemistry, and assessments of fluorescent reporter activity. All the treated animals’ developed periarticular HO with an anatomical distribution similar to human patients after arthroplasty. Heterotopic bone was found in periosteal, inter/intramuscular, and intracapsular locations. Further, the use of either PDGFRα or scleraxis (Scx) reporter mice demonstrated that both cell types gave rise to periarticular HO in this model. In summary, acetabular reaming reproducibly induces periarticular HO in the mouse reproducing human disease, and with defined mesenchymal cellular contributors similar to other experimental HO models. This protocol may be used in the future for further detailing of the cellular and molecular mediators of post-surgical HO, as well as the screening of new therapies.

Endothelial Cell Sprouting in Coronary Collateral Growth

Rationale– Coronary collateral growth is a natural bypass for ischemic heart diseases. It offers tremendous therapeutic benefit, but the process of coronary collateral growth is incompletely understood due to limited preclinical murine models that would enable interrogation of its mechanisms and processes via genetic modification and lineage tracing. Understanding the processes by which coronary collaterals develop can unlock new therapeutic strategies for ischemic heart disease.Objective– To develop a murine model of coronary collateral growth by repetitive ischemia (RI) and investigate the process of coronary collateral growth in adult hearts by lineage tracing.Methods and Results– A murine model of coronary collateral growth was developed using short episodes of repetitive ischemia. Repetitive ischemia resulted in robust collateral growth in adult mouse hearts, validated by high‐resolution micro‐computed tomography. ROSA mT/mG reporter mice with Apln‐CreERT2 transgene were used for lineage tracing of sprouting endothelial cells to determine cellular contributions to coronary collateral growth. Two‐photon and confocal microscopy imaging revealed RI‐induced coronary collateral growth initiated from sprouting Apelin+GFP+endothelial cells. Newly formed capillaries in the collateral‐dependent zone expanded in diameter upon RI stimulation and arterialized with smooth muscle cell recruitment to form mature coronary collateral arteries. Notably, pre‐existing coronary arteries and arterioles were not Apelin+ GFP+, and all Apelin+endothelial cells arose from sprouting capillaries. HIF1α, VEGFR2, CXCR4, MCP‐1, and JAG1 signaling in the collateral‐dependent zone were also upregulated during coronary collateral growth.Conclusions– We developed a murine model of RI‐induced coronary collateral growth, and our data show sprouting EC contribute to coronary collateral growth in adult hearts. Sprouting angiogenesis is shown for the first time to arterialize into mature blood vessels of larger diameter in response to repetitive ischemia in adult hearts.

Lattice Boltzmann simulation of liquid water transport in gas diffusion layers of proton exchange membrane fuel cells: Parametric studies on capillary hysteresis

Water management is crucial for reliable operation of Polymer Electrolyte Membrane Fuel Cells (PEMFC). Here, the gas diffusion layer (GDL) plays an essential role as it has to ensure efficient water removal from and oxygen transport to the catalyst layer.In this study water transport through porous carbon felt GDLs was simulated using a 3D Color-Gradient Lattice Boltzmann model. Simulations were carried out on microstructures of plain and impregnated fiber substrates of a Freudenberg H14. The GDL microstructures were reconstructed from high-resolution X-ray micro-computed tomography (μ-CT). For the distinction of carbon fibers and polytetrafluoroethylene (PTFE) in the binarized microstructures an in-house algorithm was developed. The additive was specified heterogeneously in the GDL through-plane direction employing a PTFE loading profile as derived based on μ-CT image data. In the in-plane direction the additive was furthermore defined in a realistic fashion near carbon fiber intersections. Prior to parametric studies on capillary behavior a sophisticated modeling approach for semipermeable membranes had to be developed to account for experimental boundary conditions. Capillary hysteresis was then investigated by simulation of intrusion and drainage curves and subsequent comparison to testbench data.

Part 2: Oil displacement by foam injection in Hele-Shaw cell with a pattern of impermeable regions

Foam flooding is an enhanced oil recovery (EOR) technique that is used to control gas mobility, particularly in heterogeneous and fractured reservoirs. This paper aims to numerically investigate the effect of foam flooding on oil displacement efficiency at the fracture scale. Also, an empirical model for relative permeability, which remains difficult and troublesome to measure, is proposed and implemented in the numerical model. The experimental data used in this study include five injection methods that are water, gas, tertiary gas, foam, and tertiary foam. Fluid injection was performed through 2D-printed models of an actual rock cross-section, which was obtained from high-resolution micro-computed tomography. In the numerical model used, pressure and saturation equations of injected fluids were solved using the COMSOL software.Based on the findings, both experimental data and numerical simulation results of the five injection methods were in good agreement, which shows the robustness of the proposed relative permeability model with a single fitting parameter. The oil recovery factor predicted using the proposed model outperformed that of the Buckley-Leverett and Brooks-Corey models. Also, the relative permeability model was further tested against coreflooding experimental data from the literature. This study provides more insight into numerical modeling of foam flooding at the fracture scale. Moreover, we believe that the proposed relative permeability model is robust and capable of capturing the evolution of relative permeability with saturation along the injection process, which encourages further investigation and improvement by the subsurface community. Further field-scale studies, including sensitivity and optimization, can be performed based on this work.

Characterization of Two-Phase Flow from Pore-Scale Imaging Using Fractal Geometry under Water-Wet and Mixed-Wet Conditions

High resolution micro-computed tomography images for multiphase flow provide us an effective tool to understand the mechanism of fluid flow in porous media, which is not only fundamental to the understanding of macroscopic measurements but also for providing benchmark datasets to validate pore-scale modeling. In this study, we start from two datasets of pore scale imaging of two-phase flow obtained experimentally under in situ imaging conditions at different water fractional flows under water-wet and mixed-wet conditions. Then, fractal dimension, lacunarity and succolarity are used to quantify the complexity, clustering and flow capacity of water and oil phases. The results show that with the wettability of rock surface altered from water-wet to mixed-wet, the fractal dimension for the water phase increases while for the oil phase, it decreases obviously at low water saturation. Lacunarity largely depends on the degree of wettability alteration. The more uniform wetting surfaces are distributed, the more homogeneous the fluid configuration is, which indicates smaller values for lacunarity. Moreover, succolarity is shown to well characterize the wettability effect on flow capacity. The succolarity of the oil phase in the water-wet case is larger than that in the mixed-wet case while for the water phase, the succolarity value in the water-wet is small compared with that in the mixed-wet, which show a similar trend with relative permeability curves for water-wet and mixed-wet. Our study provides a perspective into the influence that phase geometry has on relative permeability under controlled wettability and the resulting phase fractal changes under different saturations that occur during multiphase flow, which allows a means to understand phase geometric changes that occur during fluid flow.

Part 1: Oil displacement by foam injection in Hele-Shaw cell with a pattern of impermeable regions

Gas flooding is one of the most effective enhanced oil recovery (EOR) techniques. However, mobility control of the injected gas has always been an issue, especially for heterogeneous and fractured reservoirs. There is still a need to understand the phase interference (relative Permeability) and oil production from such heterogeneous and fractured systems. This study investigates the displacement of oil in a fractured system, conducted in a Hele-Shaw set up with a pattern of obstructions or impermeable regions. This 2D pattern is printed from an actual rock cross-section, obtained from high-resolution micro-computed tomography. Different displacement fluids were utilized, including water, gas, and foam in secondary and tertiary injection modes. Relative permeability curves were generated, which depict the interference between the phases flowing through the Hele-Shaw cell with tortuosity. The results showed that secondary foam injection is the most efficient technique as opposed to the other methods. Also, N2-foam achieves better recovery than air-foam, which is due to the solubility of N2 gas in the aqueous phase. This study provides more insight into foam flooding when high surfactant concentration is used. Under this condition, the effectiveness of foam injection compared to conventional water and gas injections is due to both emulsification and foam displacement effects.

Anatomical Characterization of the Tear Trough and the Lid-Cheek Junction: An Iodine Staining Technique Based on High-Resolution Micro-Computed Tomography.

The literature presents the tear trough and lid-cheek junction's controversial anatomical explanations. In this study, the authors explored the anatomical characterization of the tear trough deformity and lid-cheek junction. Twelve human cadaver specimens were obtained from the authors' anatomy department. Iodine staining and high-resolution micro-computed tomography was used to observe the suborbital area's anatomy. Anatomical studies and histologic evaluation were performed. The orbicularis retaining ligament is composed of a main septum right on the rim and multiple fibrous septa in the retro-orbicularis plain. The septum arises from the deep fascia of the palpebral part of the orbicularis oculi at approximately the level of the medial corneoscleral limbus, anchors the muscle to the orbital rim, and continues laterally as the lateral orbital thickening at the lateral canthus. Along the lid-cheek junction, multiple fibrous septa emanating from the deep fascia of the orbital part of the orbicularis oculi converge to the above septum. Using three-dimensional simulation, the skin-insert junction between the pre-palpebral part of the orbicularis oculi and pre-orbicularis oculi fibers precisely corresponded with the tear trough and the lid-cheek groove. Anatomical studies and histologic evaluation confirmed these observations. The orbicularis retaining ligament's subtle anatomical features are clearly seen using the approach described. The tear trough and the lid-cheek junction's anatomical characterization is defined by a suborbital ligament-fascia system whose description has implications in designing lower eyelid cosmetic surgery.

Salamander braincase morphology as revealed by micro-computed tomography.

Morphological data sets are misleading in salamander (Caudata) phylogeny due to the relative homoplasy of the dermal skull observed in paedomorphic forms, leading to the trend of excluding morphology when exploring questions of salamander phylogeny. Investigations in caecilians (Gymnophiona) have demonstrated that the inclusion of braincase morphology can rescue morphological phylogenetic analyses and produce topologies congruent with molecular data sets. We scanned 28 species (25 genera) of salamander, representing all 10 families, with high-resolution micro-computed tomography to investigate braincase variation. We describe the morphology of the braincase for all 10 families and distinguish between paedomorphic and metamorphic morphologies. Our results demonstrate a general uniformity amongst metamorphic species with variation largely restricted to the occipito-otic region. A greater range of variation is observed within paedomorphic forms than would be expected when considering the homoplasy of the dermal skull. Obligate paedomorphic forms demonstrate considerably more variation in the anterior braincase than do facultative paedomorphs, which we suggest is evidence of a greater complexity in the evolution and development of these forms than neoteny alone would produce. This raises the question of character independence within morphological data sets and warrants further investigation into the correlation of other characters before morphological data are omitted.

The essential role for endothelial cell sprouting in coronary collateral growth

RationaleCoronary collateral growth is a natural bypass for ischemic heart diseases. It offers tremendous therapeutic benefit, but the process of coronary collateral growth isincompletely understood due to limited preclinical murine models that would enable interrogation of its mechanisms and processes via genetic modification and lineage tracing. Understanding the processes by which coronary collaterals develop can unlock new therapeutic strategies for ischemic heart disease. ObjectiveTo develop a murine model of coronary collateral growth by repetitive ischemia and investigate whether capillary endothelial cells could contribute to the coronary collateral formation in an adult mouse heart after repetitive ischemia by lineage tracing. Methods and resultsA murine model of coronary collateral growth was developed using short episodes of repetitive ischemia. Repetitive ischemia stimulation resulted in robust collateral growth in adult mouse hearts, validated by high-resolution micro-computed tomography. Repetitive ischemia-induced collateral formation compensated ischemia caused by occlusion of the left anterior descending artery. Cardiac function improved during ischemia after repetitive ischemia, suggesting the improvement of coronary blood flow. A capillary-specific Cre driver (Apln-CreER) was used for lineage tracing capillary endothelial cells. ROSA mT/mG reporter mice crossed with the Apln-CreER transgene mice underwent a 17 days' repetitive ischemia protocol for coronary collateral growth. Two-photon and confocal microscopy imaging of heart slices revealed repetitive ischemia-induced coronary collateral growth initiated from sprouting Apelin+ endothelial cells. Newly formed capillaries in the collateral-dependent zone expanded in diameter upon repetitive ischemia stimulation and arterialized with smooth muscle cell recruitment, forming mature coronary arteries. Notably, pre-existing coronary arteries and arterioles were not Apelin+, and all Apelin+ collaterals arose from sprouting capillaries. Cxcr4, Vegfr2, Jag1, Mcp1, and Hif1⍺ mRNA levels in the repetitive ischemia-induced hearts were also upregulated at the early stage of coronary collateral growth, suggesting angiogenic signaling pathways are activated for coronary collaterals formation during repetitive ischemia. ConclusionsWe developed a murine model of coronary collateral growth induced by repetitive ischemia. Our lineage tracing study shows that sprouting endothelial cells contribute to coronary collateral growth in adult mouse hearts. For the first time, sprouting angiogenesis is shown to give rise to mature coronary arteries in response to repetitive ischemia in the adult mouse hearts.

Using High-Resolution Digital Photography and Micro-CT Scanning to Investigate Deathwatch Beetle Damage to an Historic Timber from HMS Victory

ABSTRACT Wood-boring insects such as the deathwatch beetle can cause significant damage to historical artefacts and timbers, but the extent of internal damage (and tunnelling activity in general) can be difficult to understand and quantify without the use of destructive sampling techniques. This study explored the potential of high-resolution photography and micro-computed tomography (micro-CT) to investigate beetle activity and inform on the extent of internal damage to a timber from HMS Victory. Micro-CT imaging has allowed the visualisation of deathwatch beetle activity within the timber, revealing differences in tunnelling behaviour preferences for adult and larval forms. Digital techniques were developed to determine the surface area of flight holes on some wooden blocks but were less successful for those blocks where the external surfaces were darkened with age. It was not possible to accurately determine the internal volumes of beetle tunnels within blocks of timber due to the presence of frass, which was found to be virtually indistinguishable digitally from the wood matrix.

Impaired bone quality in the superolateral femoral neck occurs independent of hip geometry and bone mineral density

Skeletal adaptation is substantially influenced by mechanical loads. Osteocytes and their lacuno-canalicular network have been identified as a key player in load sensation and bone quality regulation. In the femoral neck, one of the most common fracture sites, a complex loading pattern with lower habitual loading in the superolateral neck and higher compressive stresses in the inferomedial neck is present. Variations in the femoral neck-shaft angle (NSA), i.e., coxa vara or coxa valga, provide the opportunity to examine the influence of loading patterns on bone quality. We obtained femoral neck specimens of 28 osteoarthritic human subjects with coxa vara, coxa norma and coxa valga during total hip arthroplasty. Bone mineral density (BMD) was assessed preoperatively by dual energy X-ray absorptiometry (DXA). Cortical and trabecular microstructure and three-dimensional osteocyte lacunar characteristics were assessed in the superolateral and inferomedial neck using ex vivo high resolution micro-computed tomography. Additionally, BMD distribution and osteocyte lacunar characteristics were analyzed by quantitative backscattered electron imaging (qBEI). All groups presented thicker inferomedial than superolateral cortices. Furthermore, the superolateral site exhibited a lower osteocyte lacunar density along with lower lacunar sphericity than the inferomedial site, independent of NSA. Importantly, BMD and corresponding T-scores correlated with microstructural parameters at the inferomedial but not superolateral neck. In conclusion, we provide micromorphological evidence for fracture vulnerability of the superolateral neck, which is independent of NSA and BMD. The presented bone qualitative data provide an explanation why DXA may be insufficient to predict a substantial proportion of femoral neck fractures. Statement of significanceThe femoral neck, one of the most common fracture sites, is subject to a complex loading pattern. Site-specific differences (i.e., superolateral vs. inferomedial) in bone quality influence fracture risk, but it is unclear how this relates to hip geometry and bone mineral density (BMD) measurements in vivo. Here, we examine femoral neck specimens using a variety of high-resolution imaging techniques and demonstrate impaired bone quality in the superolateral compared to the inferomedial neck. Specifically, we found impaired cortical and trabecular microarchitecture, mineralization, and osteocyte properties, regardless of neck-shaft angle. Since BMD correlated with bone quality of the inferomedial but not the superolateral neck, our results illustrate why bone densitometry may not predict a substantial proportion of femoral neck fractures.

How Do Roots Interact with Layered Soils?

Vegetation alters soil fabric by providing biological reinforcement and enhancing the overall mechanical behaviour of slopes, thereby controlling shallow mass movement. To predict the behaviour of vegetated slopes, parameters representing the root system structure, such as root distribution, length, orientation and diameter, should be considered in slope stability models. This study quantifies the relationship between soil physical characteristics and root growth, giving special emphasis on (1) how roots influence the physical architecture of the surrounding soil structure and (2) how soil structure influences the root growth. A systematic experimental study is carried out using high-resolution X-ray micro-computed tomography (µCT) to observe the root behaviour in layered soil. In total, 2 samples are scanned over 15 days, enabling the acquisition of 10 sets of images. A machine learning algorithm for image segmentation is trained to act at 3 different training percentages, resulting in the processing of 30 sets of images, with the outcomes prompting a discussion on the size of the training data set. An automated in-house image processing algorithm is employed to quantify the void ratio and root volume ratio. This script enables post processing and image analysis of all 30 cases within few hours. This work investigates the effect of stratigraphy on root growth, along with the effect of image-segmentation parameters on soil constitutive properties.

Large Scale Analysis of Osteocyte Lacunae in Klotho Hypomorphic Mice Using High-Resolution Micro-Computed Tomography

Large Scale Analysis of Osteocyte Lacunae in Klotho Hypomorphic Mice Using High-Resolution Micro-Computed Tomography